Electrical reproducing device



March 31, 1936.

c. P. MITCHELL 2,036,091 ELECTRICAL REPRODUCING DEVICE Filed Dec. 4,1931 3 Sheets-Sheet J,

INVENTOR dim/a WZW WZAW ATTORNEY-7 March 31, 1936. c T E 2,036,091

ELECTRICAL REPRODUCING DEVICE Filed Dec. 4, 1931 3 Sheets-Sheet 2 O M I15 e 4 ,27 Z 14 g 25 if E 45 n L a 17 40 INVENTOR ATTORNEYJ March 31,1936. c. P. MITCHELL ELECTRICAL REPRODUCING DEVICE Filed Dec. 4, 1931 3Sheets-Sheet 3 INVENTOR ATTORNEYS Patented Mar. 31, 1936 ELECTRICALnnrnonucnvo DEVICE Curtis P. Mitchell, Cincinnati, Ohio, assignor to ThePalmer Company, Cincinnati, Ohio, a corporation of Ohio ApplicationDecember 4, 1931, Serial No. 579,038

4 Claims.

This invention relates to electrical apparatus and is particularlydirected to an apparatus or system for electrically reproducing motionat a location remote from the location at which it is applied. Morespecifically, the invention is utilized as an electricallyoperated'system for reproducing, recording, or showing temperatures atpoints removed from the environment, the temperature of which is beingdetermined. 1

It is an object of this invention to provide an apparatus or systemiorelectrically reproducing thermostatically detected temperature changesby means of a unit placed at the environment of heat change which may bea theatre, an oven, etc and connecting this unit by electrical means toa receiving unit which may be located at a remote point such astheoutside of the theatre or the recording room of a bakery or extremelyremote points, the receiving apparatus receiving signals from thesending device by electrical control and converting them into mechanicalthis character which is extremely sensitive and which, therefore,transmits the very slightest change in temperature and immediatelydisplays or records the change simultaneously with the occurrencethereof. Moreover, it is arranged that, in the event of power failure inthe electrical connecting means between the sending and receivingdevices, these devices will automatically operate when the power isrestored for quickly and accurately reproducing the temperature readingexisting at the time of power restoration without requiring anyresetting of the apparatus. For this purpose, the synchronousarrangement of the devices is not destroyed by power failure and therelation of the position of the temperature actuated element relative tothe temperature is constantly maintained.

It is a more general object of this invention to provide a system andapparatus for electrically electrical elements andconnections of thepresent apparatus and system.

Figure 2 is a top plan view of the sending unit showing the mechanicalconstruction thereof in detail. I

Figure 3 is a side view of Figure 2, further detailing the sending unit.

Figure 4 is a front view, partly broken away, of the recording unit. I

Figure 5 is a side view ofFigure 4, certain parts thereof being showninsection for more fully illustrating the structure.

Figure 6 is a bottom view of the recording unit.

Figure 7 is a sectional view taken on line 1-1, Figure 6, detailing theelectrical connections to the conductor fingers which control theoperation of the recording motor. 7

Figure 8 is a diagrammatic view illustrating a portion of the wiring forthe purpose of showing vthe voltage connections for alternate operationof the motors, this view illustrating the sending motor in operation.

Figure 9 is a diagrammatic view similar to Figure 8, but showing thereceiving motor in operation and the connection effective for'pre- '25venting concurrent operation 01' the sending motor. v y In practice, thepresent invention is constructed in two units, namely a sending unit Itand'a recording unit H, connected by electrical wiring, the distancebetween these units being immate rial since it may range from adjacentlocationsto verw remote locations. The apparatus is appliedfor'recording temperature in the present illustration. In practice itmay. be arranged that the sending apparatus or unitis located adjacentan oven, as in abakery, with a thermally sensitive member disposed inthe oven and the recording unit may be located in the omce or anexecutive room as when the apparatus is appliedto 0 a large institution.

The sending unit 10, generally described, includes a motor II, athermally sensitive member I: operatively carrying a contact l4,contacts I, I5, one foreach direction of the motor, these contactsalternately engageable by. the contact I! of the thermally sensitivemember, a contactor l5 driven by the motor 12 adapted to cooperate witha series of stationary contacts 11 for sendme through recordingimpulses, the motor transmission including a transmission connection I.to the two contacts thereof for the purpose of moving the same anddisestablishing contact after a certain temperature change has beenfully recorded. 66

Referring specifically to Figure 2, the motor I2 is mounted on a panelboard l9. As an example, 110 volts are supplied to the motor throughelectrical leads 2!) and 2|. The sending motor re- 1 quires around 90 to100 volts for operation. One

of. the leads on the panel board, namely 20, is

connected directly to the motor ,and the other,

namely 2|, is connected to the outer end of the thermallysensitivemember l3. The member l3 to the panel I9.

is a Bourdon tube being filled with an expansible liquid whereby thetube coils and uncoils as the temperature changes occur and transmitsmovement. I j e The inner end. of this coiled tube is fastened to thepanel board by means of an anchorage 23. The inner end,of the tube l3includes an axially extended tube portion l3 which passes through thepanel l9 and may be situated more directly in the environment of theheat, as through the side of an oven. The outer end of the Bourdon tubecarries a contact arm 24 to which the lead 2| is connected, the outerend of the contact arm 24 including ,the contact l4 providing contactfaces disposed at opposite sides thereof. These contact faces,respectively, are adapted tooper- T ate for making or breaking contactwith the contacts l5, l5, constituted by the heads of screws mounted ina carrier block 25.

The carrier block 25 comprises a nut 26 translated by a motor drivenscrew 21 and arms 28 of insulation attached to the'nut at each endthereof. Each of these arms mounts a respective contact IS, the headsofthe contact screws being opposingly related. Each of the contactscrews are. connected to the motor by a respective lead 29 and thewiringof the reversible motor as shown in the .wiring diagrams is arranged sothat contact of the thermostatically operated contact with a particularcontact screw produces a re- 'spective direction of motor operation.

The motor shaft 30 includes a pinion 3 2 drivinga gear 33 pinned to thescrew shaft 21. The screw shaft 21 is mounted in brackets 3| attachedRotation of the screw-shaft translates the carriage 25, the direction ofthe thread onthe screw being such that upon a contact with one of thecontact screws, the resultant rotation of the motor movesthe particularcontact screw 15 away from the contact for disestablishing the contactafter the thermostatically moved contact becomes stationary and the full.temperature change in the'particular direction has been recorded. Inorder to prevent rotation 1 of the nut 26 with the' screw shaft, an arm34 extends. downwardly from the nut-and-includes a channel 35 engaging aguide 36 inparallelism with the screw shaft and secured to the panel I9.

The screw shaft carries the moving contactor |6.on its outer end, thiscontactor consisting of a piece-of spring plate attached betweencooperating'nuts 31. The intumed end of the spring plate contactor movesover the series of segmental statrical lead it extends to-a terminal 4|:mounted g on the panel. Thusit is seen that as long as the thermallysensitive member is active due to temperature change, the contact l4thereof is moved against one or the other of the screw contacts I 5' androtation of the contactor l6 continues, the contactor moving from onesegmental plate I! to another in its course of travel. It will be notedthat these segmental contactor plates of which there are three in thisinstance, are spaced apart sufficiently for the contactor finger to beentirely clear of any plate at the time of its passage from onecontactor plate to another. The purpose of this will be made fullyapparent at a subsequent point in this description.

' There is a fourth terminal 44 on the panel board Hi to which thecurrent is supplied from the other input or supply terminal 42 by anelectrical lead 43. From these four terminals, electrical leads 45, 46;extend any distance required to the receiving or recording apparatus,the circuit from 43, terminal and lead as one side and through Therecording unit 11 includes a-pilot motor of the reversible type, a.recording instrumentality or stylus 4'| actuated by a motor 48, anexempliflcation of which will be given later, and a double contactor 49driven by the motor including. diametrically opposite contacts 50, 50,-connected to the respective sides of the motor wiring .for reversalthereof. This plural contact on the motor shaft is adapted to engagesegmental con tact plates 5| of the same nature and general arrangementas the contacts I! on thesending unit "I.

The recording instrument in this instance, described in detail, consistsof a base plate 52 upon which is secured a face plate or support 53 fora rotating disc 54 having graph markings thereon including a relatedtemperature scale and time chart, the degrees of temperature arrangedfrom low at the inside circle to high at the outside circle, and thetime chart constituted by hour lines on the line taken by a direct:swing of the recording pencil 55 across the temperature indicatingcircles. Thisface plate 53 is supported by brackets 53': Thedisc 54,which may be of disc against a shoulder 60 of the shaft.

The motor which controls the position of the recording finger isapproximately a 30 volt motor and its control is accomplished throughthe segmental plates 5|, and the contactors 50, previ-. ously described.V

' The finger SI of the recording device 41, which carries the pencil ora writing instrumentality of any sort, is mounted on a pivot rod 62 atits lower end and includes a hub 63, to which hub a second finger 64.isattached, this finger outer end engaged over a-pin 66 extending from anut 61 translatably mounted on a screw shaft 68 driven by the motor 48."The motor shaft 69 includes a worm l0 driving a worm wheel 1| pinned onthe screw shaft 168.. The screw shaft 68 is mounteddn bearing brackets12 attached to the base panel 52 of the unit.

1 Upon one end of this shaft and associated with the stationary contacts5| mounted on one of the bearing brackets l2 are the contactors 5|, 5|previously referred to. The contactors SI, 58 are disposed at respectivesides of the .bearing bracket 12 and are suitably insulated from eachother and from the shaft. Each transmits electrical energy to the motorthrough a respective brush I3, I3. These motor control contactors 5|, 5|each consistof a blade having an inturned outer end ridingupon thecontact plates 5| attached to the bearing bracket or panel 12. Sincethis bearing bracket is formed of insulating material, the contactplates are always from each other. The contact plates 5| are sectional,each including sections disposed upon the respective, sides of the panelor bearing brackets. These sections are duplicates as to length andposition and are electrically joined and fixed to the panel by means ofscrews llfconnecting the same through the panel.

of which hub a brush IS in the form of a spring blade is disposed. Inthe-instance of the inner assembly,- a shoulder is provided on thescrew.

an electrical lead 82 connectedthereto extending from terminals 83. onthe base panel 52. The

terminals 88 are connected to the sending unit.

II by means of the leads 4'6, any one of these connections representingone side of the current flow from the sending device. The contactors 50,5| on the receiving device are diametrically related so that they bearupon diiferent contacts SI of thestationary series. The brushes 13 whichare attached tothe base panel of the unit are connected to the wiring ofthe motor by leads '4. for respective directions of drive thereof. Theother side for the current flow to the motor l8 comes through the leadfrom the sending device to a terminal I! on the panel 52 of thereceiving unit II and thence to the motor 48 through a l8.

Operation of thc system The drawings (see Figure 1) illustrate thedevice at rest, each of the respective contactors II, II, 50, on thesending unit II and the receiving or recording unit H having coastedfrom one contactto the next adjacent contact, the inertia of the motorsl2, ll, being sufilcient for this purpose. .The swinging contact itcarried by the h rmally sensitive element IS on the sending unit II ispoised midway between the reversing contacts II, II at this time. i

As the temperature rises or falls and the thermally sensitive member iseffected, the swinging contact I thereof moves into contact with eitherone or the other of the contacts I5, I, carried by the carrier 2. Thisestablishes a circuit through to the motor l2 either for right or lefthand drive,

. the current travelling tothe motor through the direct connection 20and through the connection 21 to the contact arm 24 of the thermallysensitive member, thence passing from contact I into one or the other ofthe contacts l5 and to the particular wiring of the motor I! by way ofone of the leads 2!. This starts the motor in one or the otherdirections and the screw shaft 21 is thereby rotated moving thecontactor IS the length of the particular stationary contact II on whichit is resting at the time, whereupon it clears that contact and touchesthe next contact I 'l a It will be noted that the contactor ii of thesending unit In and the contactors 50 of the receiving unitare relatedto provide that the contact 'll upon which the-contactor l6 ofthesending .unit first moves connects the electrical energy to a deadcontact 5! of the series on the,

receiving unit, that is to say, one which is not contacted at the timeby either of the contacts 50. However, as the contactor 16 leaves theparticular contact I! and engages the next contact .ll, it will thenestablish an electrical connection from the-main line input terminal 39through the particular contact I l, thence through a particularelectrical connection 46 between the to the second contact 5| of thereceiving unit which, due to the fact that one of the pair of contactors50 of the receiving unit is resting, thereupon, connects the currentthrough said contactor 50 to the particular side of the receiv- 7 ing orrecording motor 48 which is active through its transmission for causingmovement of the recording finger SI swinging the same in an are Igenerally radially relative to the rotating recording disc drawingthereupon a line indicating the rise or fall in temperature.

It is arranged that the motor ll of the sending unit It! will notoperate when the motor 48 of the receiving. unit is operating due tovoltage and resistance conditions, which will be hereinafterd8SCl'ib'3duS0 that the moment the contactor of the sending unitestablishes the circuit for the impu se to the receiving motor, thesending motor stops momentarily. In the preceding description, themovement of the respective contactors has been assumed tovbe clockwise,it being ap parent thatif the swinging contactor ll of the thermallysensitive element l3 has moved to the opposite. contact l5,anticlockwise movement of these contactors would have resulted and thecurrent fiow would have been established to the receiving or. recording.motor 8 by way of the third contactors l1, SI of the respective series.

Going back to thefirst description, it will be apparent that whenthereceiving orrecording motor 48 has been set in motion. it will move. bymeans of the shaft 88, the contactors 58, 50 which control it until theparticular one being described leaves the second contact of the seriesof the recording or receiving unit, at which time the re-.

cording motor will stop for the reason that the next contact is a deadone, that is, not connected through'to the main line by way of a contactI! of the sending unit.-

As soon as the recording motor 48 stops, the sending motor I! will againstart, since there is then suificient voltage for operation, and thecon- .tactor l5 thereof will move to the third contact 41 in a ciockwisedirection. This again establishes cur as long as the thermally sensitivemember is eifected by temperature changeand is continuing a rise or fallsince the swinging contact will be continually urgedagainstthe-particular contest 15 even though the sending motor iselective for 'slowly -,drawing the contact it away from the swingingcontact, the pitch of the screw 2'! beingproportioned for aslow'movement of the nut car'- v 1 sistor brin 92.6-volts across theresistance moried contacts l5, l5. s l The moment; the rise. or fall oftemperature ceases, the sending motor I! will be-eflective-for lbreaking the contact betweencontacts ll i5 and disesta'blishingthecircuit to the sendingmotor by its own action. The swinging contact IIis related to the contact screws l5, so that a very slight movementthereof is eflective for recording a temperature change,.since themaking and breaking of contact requires. very little movement, thusresulting in a very sensitive recording or display of temperature. Itisapparent that the thermally sensitive element 13 may be of any typedesired and capable of imparting a motion to a particularidouble contactalong the lines of that described.

f It is,necessary that the sending motorpause or operate intermittentlyfor preventing the con- 2 tact l6 operated thereby from.running ahead asstated before, the sending motor and the reapproximately 400 olimafiTherefore, the drop of the contactors 50, 59 of the receiving deviceandfor keeping these contacts in perfect relation for establishing .tbesuccessive circuits through the respective electrically connected sta-'tionary contacts 11, Si, of the units. Therefore,

oeiving motor cannot operate concurrently. As a practicalelectrical'arrangement for accomplishing this result a resistance 90 of75 ohms is inserted in the main line, this resistance being inserted infront of both .0!- the motors.- The larger motor l2,-namely. the sendingmotor. requires -90 volts or-over for operation.

This motor I: is calculated at a resistance or across resistance 90 is17.4 volts (see later quations and Figures 8 and 9 of the drawings) andthe input voltage to the sending motor is 92.6

volts; Since the sending motor will operate on 90 volts or more, thevoltage 92.6, being the maximum supply to the sending otor, will besufflcient for operating this motor. However, when the contact "of therecording unit closes the circuit through to the recording motor. 59,thereby shunting the sending motor,

neglecting the conductance of the. sending motor, the voltage will be asfollows: Since the receiving motor ar -recording motor 48 is calculatedto operate on a voltage of from 25 to 30 volts and has been arranged ata resistance of about 25 ohms, thevoltage drop through ,the resistancefigures at 82.5 volts and the voltage across the motors at 27.5 volts.ginceithe voltage drop throughthe .jll is now 82.5 leaving only 27.5volts input to the sending" 1 motor ii, the: sending motorisinoperative.

Therefore, the two motors work intermittently and alternately, thesending m'otorclearing' one contact which-requires a certain amoimt oimovement equivalent to about one third revolution of the shalt and makesanother, the making of the second contact establishing the circuit tothe recording motor which operates as long. as a particular'contact ismaintained which is equivalent to about one-third revolution of thecontactor driving shaft of this unit. I o

Otherwise stated, the sending motor stops due tolack of suillcientvoltage to operate it when the receiving motor. is connected. Thevoltage applied across the, terminals 39 and "can be considered asconstant, say at 110 volts; When thesending motor-l2 with-the resistanceof 400 Ohms is-ponnected across the line in series with resistor90501375 ohms, and motor 49 is disconnected, a shown in Figure 8, the110'vo1ts are divided mmga drop of 17.4 volts across the retor 12. Sincethis motor requires over volts, it will with this@ connection. If themotor 4!; with aresistance of 25 ohms is connected in parallel withmotor 12, the combination in series with the resistor9il, as. shown inFigure 9, motor 12 will not run. The motor, resistance of motors l2 and48, of 400 and 25 ohms respectively, in parallel have a seriesresistance equiv- I alent to 23.5 ohms, making the total resistanceacross the .line, the 75 ohms of resistor 90, plus the 23.5 ohmsequivalent resistance which is.

98.5 ohms. The current through-resistor so at; voltsjis 110 divided by98.5 or1.12 amperes.

The voltage drop across resistance 90 is 1.12 times 75, or 83.7 volts,leaving a voltage drop of 26.3

across each of the motors l2 and 48. .Since motor "requires 90'v'olts ormore, it will not run,

. but,m'otor 48, 'requiringfrom 25 to 30 volts, will run on the 26.3volts available. The. increase in current, due to the currentrequirements of motor 48, has increased the voltage drop across resistor99 to such an extent that the remaining volts oi the 110 volts of theline are insuflicient to operate motor 12. Thus the circuit whichcomtoFigures 8 and 9 for the following equations.

- From Figure 8 the following equations are drawn which will explain indetail the voltages eiIective-forpermitting operation of the sendingtor-is in open circuit'and the sending motor is operative. When thecircuit is closed to the recording'or receivlngmotor, referring toFigure 9, the

equations neglecting the'resistance of the motor I: will be as follows:

\, 25 7 il-76X 110-27-5 volts.

These equations are based on' the voltages coming. through therespective" input leads and the respective resistances when the entirecurrent or recording motor. 1t willbe apparent that due to this wiringarrangement, the synchronized action of the units is always maintainedand'mere particularly the relation of the thermally sensitiveelement andthe recording finger is always maintained.

Having described my invention, I claim:

1. The combination with a temperature recording device of a thermallysensitive element including a movable contact, a motor, electricalconnections to said motor, a resistor in one of said electricalconnections, one of said electrical connections including said movablecontact, a pair of motor control contacts alternately engageable by saidmovable contact for starting and direction control of said motor inreversing directions, means driven by said motor for disestablishingcontact between said motor control contacts and said movable contact, acontactor driven by said motor, a series of contacts suc-\ 'cessivelyand independently engageableby said contactor, a second set of contactslocated at the point of temperature record corresponding in number tothe first set, the corresponding contacts of said sets of contactsrespectively in electrical connection, a motor driven contactor elementfor traversing the contacts of said second set, said contact elementnormally out of phase one contact with respect to the contactor of saidfirst set of contacts, a motor driving said contact element andelectrically connected thereto for eifecting its own stopping control,said second series of contacts arranged relative to said con-. tactelement whereby contact between said element and a contact of the seriesis always maintained, said second set of contacts and said contactorelement constituting a switch controlling the completion of thecir'cuitof the motor driving the same through a circuit including a contact andthe contactor of said first series, said second motor when in electricalconnection with said second contacts arranged to be in parallel withsaid first motor, and said motors when parallel connected arranged to bein series with said resistor, said first motor requiring substantiallyline voltage for operation, said second motor requiring relatively lessthan line voltage for operation, said motors having resistances adaptedwhen connected in parallel with each other and in series with saidresistor to reduce the voltage to a value suflicient to operate only thesecond motor and insuflicient to operate the first motor.

2. Switchgear for remotely electrically indicating physical change,comprising, a pair of multiple switches, each comprising a plurality ofcontacts and a contactor element for traversing the same, the respectivecontacts of said switches respectively in electrical connection, motorsfor respectively driving each of the contactors of said switches, saidmotors in common partial circuit connection, a resistance included inthe circuit to one of said motors, the contactor of one of said switcheselectrically energized, the contactors of said switches normally out 01'phase one contact, a pilot switch having an element responsive tophysical change alternately oooperating with oppositely arranged contactelements for starting and direction control of one of said motors inreversing directions, said oppositely arranged contacts mounted forunitary movement to disrupt and alternate motor direction controlthrough said pilot switch element responsive to physical change, themotor of said second switch in circuit completing connection with saidfirst motor through the contactor of said second set of contacts anddriving said second contactor to effect its own stopping control, saidmotors electrically connected to be in parallel when said partial commoncircuit is completed through said second switch and in series with saidresistance, said second motor requiring comparatively less line voltagefor operation than said first motor, whereby the magnitude of theresultant voltage in the circuit when the motors are so connected isinsufilcient for operation of said first motor but suificient foroperation of said second motor.

3. In an apparatus of the type-described, an electric motor drivenswitch controlling a plurality of controlling circuits, a secondelectric motor driven switch, the corresponding poles of said motordriven switches respectively in circuit connection, a thermo pilotswitch having a thermo element alternately cooperating with oppositelyarranged contact elements for starting and. direction control of one ofsaid motors, said contacts mounted for unitary movement to disrupt andalternate motor direction control through said thermo switch element,said motors in common partial circuit connection, one motor drivenswitch controlling the completion of the circuit to the other motorthrough said switch of said second motor in reversing directions foroperative control, the operation of said second motor through its switcheffecting its own stopping control, the installation of the second motorinto the circuit reducing voltage potential in the entire circuit to avalue insufiicient to drive the motor subject to theme pilot switchcontrol.

4. In an apparatus of the type described, an electric motor drivenswitch controlling a plurality of controlling circuits, a secondelectric motor driven switch, the movable elements of said switchesnormally out of phase one contact in either direction, the correspondingpoles of said switches respectively in circuit connection, a thermopilot switch having a thermo element alternately cooperating withoppositely arranged contact elements for starting and direction controloi! one of said switch motors, said contact elements mounted for unitarymovement by the motor controlled thereby, to disrupt and alternate motordirection control through said thermo switch element, said switch motorsin common partial circuit connection, one motor driven switchcontrolling the completion of the circuit to the other motor throughsaid switch of said second motor in reversing directions for operativecontrol, the operation of said second motor through its switch effectingits own stopping control, the installation of the second motor into thecircuit reducing voltage potential in the entire circuit to a valueinsufficient to drive the motor subject to thermo pilot switch control.

- CU'R'IIS P. MITCHELL.

